Telephone system



March 14, 1933. P. B. MURPHY TELEPHONE SYSTEM Original Filed Dec. 6,1950 4 Sheets-Sheet 1 GE mat Nut .0 6t

INVENTOR RRMURPHV A TTORNEV March 14, 1933. P B MURPHY 1,901,403

TELEPHONE SYSTEM Original Filed Dec. 6, 1930 4 Sheets-Sheet 2 MARG/NAL#vmvrop RRMURPH) er Wfi f ATTORNEY March 14, 1933. P. B. MURPHYTELEPHONE SYSTEM Original Filed Dec. 6, 1950 4 Sheets-Sheet 3 //v VE/Vr0)? I P a MURPHY WWV A TTORNEV March 14, 1933. MURPHY 1,901,403

TELEPHONE SYSTEM Original Filed Dec. 6, 1930 4 Sheets-Sheet 4 IN VE NTOR v St RRMURPHV 7 ATTORNE Famed lVlar. i4, 193s U ITED STATES ran s.mIBrHY, or nYAcx, nEwYonK, AssieNon. TOCQBVELIQ- 'rnLnrironnjnanonnroams, mcoarom'ran, or NEW renx, n.1, A coR-Poan'rIoN or Nnwromz;

TELEPHONE SYSTEM Application filed December 6, 1930, semi No.-oo,517.-Renewed April 157193211 {This invention relates to telephone systemsandparticularly to means for checking .ilcalling subscribers numbers andthe object of the inventionisto simplify and improve the/checking ofnumbers when applied to automatic systems.

VHeretofore systems have been proposed in whichan' operator atone officemaycheck vthe-number given by a calling subscriber at another oflice whohasestablished automaticallya connection to said operator over atrunkbetween said ofiices by establishing a separate connection to thecalling subscribers. lineand causing the application of an alter- 11,5

nating currentsignal through the automatic connection for detection bythis operator f the calling subscriber gave the correct-num- -ber.- ,Asystem of this character has been" disclosed 'in :the copendingapplication of R L. Quass, Serial No. 500,492, filed'on the same .datewith this application. In the Quass system this alternating currentsignal applied from means inthe second connection."

by the operator atthe second oflice causes the alternatingcurrent signalto be applied to the automatic connection by transmission of adirectcurrent signal over the trunk line of theautomatic connection from thesecond office to thefirst .ofiice' and by having this direct currentsignal, when receivedat the ifirstioflice,translated into thealternating current signal for transmission over aportion of theautomatic connection at the first office specific feature of thisarrange- ;.ment 'f or applying the alternating current signal is themeans for applying the direct current signal over the trunk when thistrunk is of the type in which the usual supervisory 1 signaling is donein one direction by reversal of battery and ground connections over thetip and-ring conductors and in the 5other direction by the reduction ofresistance of this battery and ground connection fover the tip andringconductors. This direct currentsignal may .be applied regardless ofwhether or not .the battery and ground. connections have'been reversed.A differen i 1 1 g Fig. 1 show ;a modified A feature of the presentinvention is an 1 arrangement in systems of this kind'where-c tiallywound relay is providedat thelfirst ofiice for the application of thealternating current signal This relay-is providedwithtwo windingsconnected in aseriesopposing direction from battery to fground through.the tip and ring conductors to jpr'event said relay from operatinginsaid, circuit regard- PATENT less of the current reversals,-and acircuit arrangement is provided whereby regardless of the currentreversalsa connection is made;

at the first office from a battery of ahigher voltage than the normalbattery-in opposition to said normal battery to cause the di rectcurrent signal therefrom"v to operate.

said relay to apply the alternating current signal.

This invention has been illustratedthe accompanying drawings 'in which 7Figs. 1'00 5 may be arranged as shown in Fig.6; v V j; Figs, 1, 2 and 3show ascomplete system for number checking; while a l Figs. 4 and5-taken in connection with" scriber 1 at office A-may. extend anautomatic connection to atoll operators posi number checking tion-TO atoflice B over; a line finder LF, a

selector S and a district selector DS and a trunk ST. The circuits atthejcall-originat-. mg end of trunk ST have been shown in Fig. 1 indetail to illustrate certain features of the invention and the circuitsfor this trunk at the toll ofli'ceB have also been shown in detail inFig. 2 to illustrate other features of theinvention. Trunk ST-ter- 301-to a desired line. ,A number; checking cord 302 hasalso been showninFig.3 in

.minates in jack 200 at the tolloper'ators podiagrammaticform. This cordmay be used for checking a calling sub'scribers number over the numbercheckingtrunk-NGT that" This number checking trunk NCT termi.-

terminates at the toll office B in jack; 201.1:

ing snbscr-ihe-fls number over the checking w terminal 105 which isconnected -to-the-sleeve The circ,uit,,details of theinumber checkingCora-ace: and? trunk NCT? {and the A j0vperators cord have not beenshown as these details do not appear to be necessary-for the clearunderstanding of the present invention and inifact any w-ellek-nownmeans may be toll operator andthe A operator in regard to her-checking.Theniodified for-in of the employed for communication between theinvention as shown in Figs. 4 and 5 shows a -;I-IIOQl l fiCZL tlODOZEthe circu ts of, trunk S1 at ithe"terminating--end in the-toll; ofiice Band 'erators p'osition :for causinge' 'the number by the subscriber at'1 to the toll operator at TO- an-dthe establishing of another connection "from the toll operator TO to the A :operatorA O' for thechecking of'the calling 1 checking signal-to be effected.- I

A -d'escript:ion" will now be made using Figs. 1,2 and of a connectionvestablished subscriber-snumber,- I

Atter the calling subscriber at l has establis'he'd a connection overline-finder 'LF,

selector Sand district selector DS to trunk '-S':1- of :any well now-nautomatic system, a

circuit is established for the operati'on-of relay-l07 as follows:battery, uppe'r outer armature and back'contact of relay108,'repe'ating'coil'1'09, upper armature and back contact of relay 110over thetip conductor through a loop connection in the district"-iselector DS, back over thering conductor, 1

---lower inner armature and back contact of re'l'ay 110, repeating coil1'09, upper inner armature and back contact of'rela y 108, up-

perwinding ofrelay 107 to ground. Relay 107 in'operatingrcloses acircuit for the op-- eration of relay 111 from battery, winding I of.relay 111, make=before break contacts of relay 112; armature and i'rontcontact? of relay :10? to ground. 'Relay 111' in op-- crating partiallyprepares a supervisory signaling circuit over trunkIST. it also es-'*tablish'es a connection to ground overits lower middle armature and iront contact, JIIlZlkG-bGfODG lJIGfik contacts of rel ay 2113,0011 "-126, 'tothe sleeve conductor 'o'f th'e district selector to maintain itbusy. 'An obvious T circuit is also prepared for the operation v ofrelay113. This relay' fin operating, sup- "closes an obvious circuit ifor theoperationof of the 200.

relay 115. This relay closes a ringing induction connection from theringing source 121 to the calling subscribers line. This relay alsoextends a connection from battery and ground through windings of relays116 and 117:, arn atures of relays: .11 5, and ;111, re-

*peatin 'coil ltll trunk ST arniatures and conductor of the callingsubscribers. line... b

,backconta-cts of relay 203, repeating coil 204;, arn atures and backcontactsoff relay '205 tl1ro'ujgh'" a loop over thewindings of relay-206; L'Rela'y 116 'd'oesnot operate in this circuit-as it isdifferentially wound and provided for number checking purposes as willE:be hereinafterdescribed1;.Neither does relay 117 operate in thiscircuit due to the high resista-nce'of the lower winding of relay 206and the marginal "characteristics- 0f relay 117. Relay 206; however,'operates and "closes a circuit for the operation of relay 207; Groundis disconnected from the -low resistance windings of relays 208 and 209by the operation of "relay 206 andthe purpose iof this will be describedin 'a connection recalling th'e tol-l operator from the sub- I scribersstation: The operation :01 relay 207:

clos'esfan obviou's' circuit for the operation line la rnpassociatedwith ack The toll operator" at" .TQ ans-wers this signal 1 by "insertingthe answering pl ug 211 of cord-300in'to jack 200. -The immediate effectof this connection 'wi ll b'e' the-operation of relays 208 and 209 froma--"-battery'= supplied over: the sleeve of cord 300130 the upperwindings of these relaysto 'ground; -Relay QOSf-inopei'ating, closes anobvious circuit for the"'operation' of relay i 212; {Relay 212, inoperating, opens "the circuit for-the line lamp 210 atits lower outerarmature-and -"back"'con='tact. -R'elay 212 also completes acir'cuit forthe windin'go f relay '205and resistance-213 tobattery at the lowerouter armature and front contact or relay 212. "The operation of relay205is, however, we ventedfdue to the ground shunt connectionatthearinature -and front contact ofrelay 209. 'The tip and ringconductors cs f Fthe trunk ST' are-now connected through the cond'enser214 "at the flipper armature-and frontron-tact of relay-212 to pr'oifidea talk-' 'ing"cir'cui t'.' Relay 2'12-also*s'lruntsatits lower innerarmature and front "contact the lower high reSiStaI-I'ce winding ofrelay 206. Relay 200,1liowever,"-rernains operated. At thecall-originatingend of trunk'."- ST, the marginal relay 1'17nowbpe'rate's due to the shunting or the high resistance Winding ofrelay 206. Relay 117inbper'ating closes an obvious circuit for theoperation of relay 120. Relay 120, in "operating; ope nsfthe ringinginduction connection from the ringsource'121' to th'e callings'ubscr'ibefis line at it'supper armature, andjbackfcontact. "IRe "lay120 also closes an 'lobyiousj" circuit for rela -113 to "hold this relayoperated to and ground connections over .the tip and ring conductortothe district selector DS to cut throughby meansin the districtselector (not shown), the tip and ring connection from thecallingsubscribers line tothe relay 107 It, will be noted thatthetalking con-- nection .from the callingsubscribers line nowextends-through both windingsof relay 107 and that relay 108 has closedat'its lower outer armature and front contact the talking connectionthrough the outgoing coil, of the. V repeating .coil- 109'. Thecircuitsare now incondition for conversation betweenthe-subscriber at 1and the toll operator at T0.-

If the calling subscribersdecides to recall.

0 the toll operator at T0 he will operate the switchhook in the usualmanner. causes the alternateloperation and release of relay 107. Relay111 being under control of relay 107 will follow these operations and 7.cause the battery and ground connections -operator at T0 that thecalling subscriber- -the calling subscriber she will operate the aterelay 110 over an obvious circuit, the ground connection for which issupplied 50. throughthe armature and front contact of r a lockingcircuit for itself under'control of over trunk ST to be alternatelyreversed. This causes the alternate release and opera-V tion ofrelay206. Relay 206,*in turn,willl alternately connect and disconnect theground from the lower windings of relays 208 and209. This'will have'theefiect of alternately lowering the resistance in the sleeve circuit-forcord 300 and thereby cause inany well-known'manner the flashing of asupervisory lamp-in this cord to notify the desires further attention. 7

If the toll operator at T0 desires tor'ecall usual ringing key in cord300 (not shown) and thereby cause the ringing relay'203'to be operatedand apply ringing current from source 214 over the tip and ringconductors of trunk ST to actuate the ringing respon sive relay 123.Ringing relay 123 will operrelay 107. Relay 110, in operating, providesrelay 11 1 independent of relay 107 and supplies'ringing current to thecalling subscribers line from source 125' and the ground return at theupper armature andfront contact ofrelay 1-10.' It will be noted thatonthe operation of-relay 110 relay 107 willrelease but relay 111 willnow be maintained operated under control of relay 114 over a circuitthrough the lower outer armature relays 123 and110. Relay110 inreleasing This again closes a circuit for'the operation of relay-5107.

After the calling subscriber instructed the toll operatorat toextend aconnection to a desired 'subscribers lineand this connection hasbeenmade and conversation completed the calling. subscribermay dis,-

connect ,by replacing; his receiver on the hook.j This causes therelease of relay 107 which in turn causes: the release of relay 111:. TRelay11'1, in releasing, releases'relay 2,06to 1 continuously "lightthev supervisory lamp. in

the cord, 300 as a disconnect signal. The

operator at T0; will now disconnect: by removing plug 211 from jack 200therebycausing thee-release jof relays 208 and 209'.vv .,-Relay 208, inreleasing, causes the release of relay 212- and this-relay inturnremoves the short circuit from the lower high resistance winding ofrelay 206 thereby, causing the release of relay 117- which, inturn,causes the releaseofrelay 120. Relay --120,'in releasing, opens thecircuit for relay 113; which, in releasing, releases relay 11 1., Therelease of these relays opens the connection to ground for the sleevecircuit-tothe district selector and causes the release ofthis selectorand the preceding switchesinthe connection to the" calling subscriberRelay .11 1 releases relays 108 and. 115 andthecircuits shown in thesezfigures are thereby returned to normal condition.-'- Ifthe tolloperator; at TOishould disconnect before the calling subscriber, relays208-, 209 and 212 will release and thereby cause thelighting of the linelamp 210. x

;The operation of these, circuits while checking the callingsubscribers' number will nowbe described. Thetoll operator will first,by operatingher-talking key in cord 300, (not shown) connect hertelephone set 303 through cord 300 to the calling subscribers line andsecure ,the number of this subscriber for the purposeofchecking it aswellas for the securingof theinformation for extending the connection ofthegdesired subscriberifiline When the operator has received :the numberofthe {call-ing subs'c'riber, she-will actuate a talking key (not shown)in the number checking cord 302." Theoperation' of this key, connectsthe telephone operators set .303 with plug 309 for number checking;-The,..toll"operator will 5 checking trunk NCT and operate key3l0.

tion of relay 311. Relay 311 in operating its a now insert plug 309 intojack 201 of a number armature opens the sleeve circuit'for the cord 300and establishes a connection from a batterypthrough this armature andits front con tact to thesleeve of cord 300 leading through plug 211 totrunk ST and also at the makeand front contact of relay 110. When theoperator at T0 discontinue's the ringing re; 65 lay 203 will release tocause the release of" before-break contacts controlled by thisarmaturecloses a circuit to ground for the will be noted that the circuit trainbatter forthe sleeve circuit to the trunk ST {passes through aresistance {312. During the -oper-' ationof relay 31 1, the sleevecircuit to the V trunk was momentarily interrupted which caused-therelease of relays 208 and 209 mo-' mentarily; \Vhen the above-mentionedcir- V cuit through resistance 312 is closed, relay 208 will againoperate, w-hi le] relay 209 which is-inargin al will remain released dueto the high resistance 312, inthe sleeve'circui't. During the momentaryrelease of re lay 208, the circuit for relay 212 was opened but thisrelay is slow in releasingso-that it resistance 21-3 causes theoperation of this relay. Relay 205, 'in operating, disconnects the relay206 from the trunk ST and thereby causes it to release. If relay 207 isoperated at this time,iit will be held operated by the operation ofrelay 205 througha locking "circuit provided at the lower armature andthese circumstances when relay 205 operates, high voltage battery andground will be 7 supplied to the line as follows: from bat-l tery andground through the windings of retardation coil-'216-, a r-matures andfront contacts of relay 207,- ar-matures and front. contacts of relay205, transformer 204?, armatures and back contact of relay 203,'tip-and;ring conductors of trunk ST. The high,

voltage battery will be connected injthis case over the ringconcluctorof trunk ST to the' battery through a winding of relay 116 ito ground, while ground at 21 6 will he connected to the tip conductorto ground at 'ated-at this time, the high voltagebattery would havebeen'connected overth-e tip con ductorand in this case the relay111would not have been-operated so the connection would have been made tothesa'rn'e battery at relay 116. This arrangement is for the. a purposeo -f insuring the operation "of relay 1 116 regardless of whethersupervision is being carriedon during this time or not. That is,regardless howthe tip and ring conductors are connected for supervisorysignaling as-hereinbetore described the battery at 216 will always beswitched to oppose the battery at 116 when number checking sig-V Ineither case, there- 0 naling takes place. fore, relay 116 will-beoperated as it is differentially wound and'the high voltage batterycauses current to flowthroughawind.

7 ing of relay 116 inthe opposite direction to age battery. Relay 116,inoperating, closes an obvious circuitfor ,theoper'ation ofirelay 112 andthis relay in operating provides a a holding circuit for-relay 1-20if ithas been i operated byrelayll'f during supervision.

will remain operated during this period.- As relay 209 is-now releasedthe circuit here: inbeiore mentioned for relay 205 through frontcontactto ground of relay 205. UnderI relay 116. If relay 207 had notbeeno'perthat ordinarily flowing from the low voltino-1 ,463

If relay 117 was not ope'rated,re lay 120 will now be operatedby-i'e'lay :112'to maintain the circuit connections established regardless ofw'hether relays-117 and-111 are operat'ed or releasedduring thenumber T check- ,in-g' period; Relay 112,in operating-"provides aconnecti'on from an alternating current source 126 totl'ie sleeve of theconnection to thercalling'subscriber 'a'ndvthe extension sleeveof' thecallin subscriberv'to vnumber"checkingterminalxjmo.i' f a "While thisnumberichecking signal being transinitted,'the tOlilz'OP'QIELtOI' willinfformbthe LA operator at position A0 of the number iofthe 'cazllingsubscriber. The num: 'ber checking trunk may: betany well-knowncommunicating circuit in which the inserti'oniof .plug 309 intojack-1201 '7 causes the operator at AO -to' be called and when thisoperatoranswers thecal'l 'hy iiisertingr the-' answering plug of cord101 into jack 101 a talking connection is "established between the two'operatorsp The A operator will then receive the number of'thesubscriber whose-number has to-be checked. 'She will then touch thechecking terminal, 105 which is marked with the numberof the callingsubscriber .withsthe tip of the ical'ling plug :of cord 104. Thisterminal may lee-mounted on the. A operators board for numb erche'ckangU-purposes'in connection with similar terminalsof-other linesthat may be checked in this manner by the operator. If an alterhatingcurrent signal is detected on the sleeveconnectionirom source 126 the-Aoperator will know that-the number given by the callingsubscribe-rwascorrect; The A operator will then communicaterwith the toll operatorandv inform her that the numbe-r given by the calling subscriberiw'a'sthe:

correct number. If, however, tl ejA operator does not receive analternating current signal on terminal 105 she Will know that thecalling subscriber gave the wrongnumber as the terminal 105 would inthat case ;be associated with another ,subscribers over the connectionestablished between the atoll operator and the calling subscriber andin-regard to the'passing of the alternating current signaltoythe-caglling subscribers sleeve; g

In signaling from the calling subscribers line over trunk, ST relay 406operates through both windings being, included in the tip and ringconnection; Relay-407 is then operated overan obvious 'circuitto preparethe circuits for numbei ghec'king. Re-

lay 406, operating, also closes an obvious circuit forthe operation ofrelay 408. This relay, in operating, closes a circuit for the.

telephone set 503 'to be connected to plug 508 for number checking' Whencord'500 was connectedto jack 400 relay 412-,was

operated from battery over the sleeve of the cord to extinguish'lamp-410,to establish a talking circuit and-to short circuit the highresistance winding" of relay 400; This causes the operation of the relay117, Fig. 1, and

the operation of the circuit in Fig. 1 is the same as hereinbeforedescribed in connection with Figs. 2 and 3. i

If thecallingsubscriber desires to recallthe toll ope rator at TO, hewill proceed as 'hereinbei'ore descri-bed'to cause the alternateoperation and release of relay 406 which, in turn, causes thealternateoperation and release of relay 408. Batteryand ground are therebyalternately connected to the tip conductor to flash the supervisorylampin the 'cord" 500.. Relay 417 is 'not'operatedfi during supervisionregardless of whether re- V lav 408 is operated or not as itisditferentially' wound.

Iffthe toll I calling subscriber, she causes alternating current to beapplied from the cord 500 to operate the alternating current responsiverelay 420 and thereby cause the operation of relay 403 to apply ringingcurrent over the trunk ST and thereby call the calling subscriber in thesamemanner as'hereinbe: fore described in connection with Fig. 1.

The toll operator, in number'checking," inserts plug 508 into jack 401and operatesa key (not shown) to connecther telephone set 503 withtrunk-NGT. She-then notifies the A o-peratorthat number checking isdesired and operates key 510. 'The opera tion of this l'keycauses theoperation of relay 511. Relay 511, in operating applies a groundconnection througha retardation coil 512 to the tip and ring conductorsof the. cord 500. This'is the essential difference fromthe signalingcaused 'byffthe op eration of relay 311, Fig, This ground connectiononthe two conductors causes the operation of relay 417 regardless ofwhether relay 408 is operated or not. Ifg'round is connected to theupper winding of relay 417 when nuinb'er checking, this" winding isshunted and thereby permits current through the lower winding to causethe operation of this relay, while if battery is connected when numberchecking, the curvoperator wishes to recall the rent in both windingsaid each other toe cause the operation of'this relay; Thus 1number'checking operations are not interfered with by supervisorysignaling. f Relay 417 in operating, closes a circuit forthe'operationof relay 405 to apply battery and groundthrough theretardation coil 416 and contacts of relays 407 and 405 to the distantend of the trunk ST to cause the operation of relay 116. In this'case,it depends upon the operation of relay 407 whether battery or groundshould be connected in one way or another tothe tip and ring conductors.

Relay 116 applies the alternating current signal to the sleeve conductorofthe calling subscriber'a's herei-nbefore described. hen the number"checking has been completed and lamp 516-"has been lighted steadily orflashed depending upon-whether the sub scriber gave the .right nu'mberor not, the toll operator removes plug 508 from jack 401 and proceedswith thesetting up of the a connection. g

While this invention 'haso'nly been described in connection with twosystems it should be understood that it can readily be applied to othersystems withoutdeparting from the spirit thereof and that thepresentdisclosures are merely illustrative of the invention-n v 7 Whatis'clanned 1s:

a '1. In a telephone"fsyste1n, a first oiiice a second oflice, asubscribers line at the first ofiice, means for establishing aconnection 5 from the subscribers line to the operators office, anoperators position at the second positionfmeans for establishing asecond connection from the operators'position to the subscribersline,means for transmitting a'direct current signal from theoperato'rsposition toward the subscribers line, and means for translating-saiddirect current signal into an alternating current signal fortransmission over said connections.

2. In a telephone system, a first oifice, a second oilice, asubscribers' line 'atgthe first oflice,an*operators position at thesecond oflice, means for, establishing, a connection from'th'esubscribers line to the operators position, said connection including asleeve conductor forthat portion thereof that is located at the firstoflice', means for estab-' lishing a'secondfconn'ection from theoperators position tothe subscribers line, means for transmitting adirect current signal from the operators position' over the firstconnection toward the firstv office, meansjfor translating said directcurrent signal into an alternating current signahfand means fortransmitting said, alternating current signal over the sleeve conductorof saidfirst connection to the second-connection.

3. In atelephone system,-a first oifice, a

second .oifice; a subs-cribers 'line at the first ofiice, an operatorspo'sition at the second has been reversediornotp 5. In a signalingsystem,'a.l1ne, a source of current for said'line, a seriesjconneot onofiice, a trunk between said oflices, means q for establishing. aconnection from the subscribers line over said trunkto said oper atorsposition, means for establishing a;

second connection from the operatorsp.osi. tion to the subscribersline,- adirect. current source associatedwith said'trunklwhile ens--gaged 111 said first connection, means for signaling in either d rectionover said trunk.

While, engaged in said first connection through reversal of the directcurrent from said source and chan es in the resistance. of

said trunk, means For transmitt-ing froin said operator s position adirectcurrent signal over said trunk of a higher voltage than the directcurrent from the source associated Withsaid trunk regardless. of the--direction of said direct current froinsaid source, means includingarelay at the first oilice responsive to the high voltage direct, currentsignal, and means respons ve to the operation of saidrelayfortransmitting an alternating current signal over saidconnections at thefirst office.

4. In a signalingsystem, a line a source of current for said line,means, for. signaling in either direction over said. line with thecurrent reversed fromthe normal direction of said current'on said line,another source of current of a higher voltage'than the normal current onsaidline, and means for signaling in one direction over said 'line withsaid increased current regardlessof Whether the direction of the normalcurrent over the tip and .ring conductors of said line: from saidsourceto ground, means-forsignaling over said linein-one directionyby revers nthe current flowiithrou hsaid cone ductors i from said source, .meansfor signals ing over said lineinthe-opposite direct-ion by reversing thecurrent from said source, and reducing the resistance of .said,connection, a relay in said connection,.means-for preventing theoperationoisaid-relay regardless of the direction of the: current fromsaid source in said connectiomasourceofi current of a higher voltagethan .the current; from the firstmentioned source on said 11116,.

means for actuating said relay on the connection ofsaid second-source ofcurrent to:

said line regardlessofthe direction of the original current from thefirstmentioned source. through said connection.

6. In a signaling system, two ofiiccs, a. line betweensaid ofliceshaving a sleeve conduc-, tor at one oilice, a source of current-at oneoilice for said line, means for signaling in either direction overthetip. and ring conductors of saidv line with. the current-me versed fromthe normal direction 1 of said current on the said line,.a polar zedrelay in said line at one ofiice, meansfomnaintain.

Lemma ing'saidrelay in non-operated condition res gardless of thedirection of the current on.

said line, means including a source of cure rentv of. a higher voltagethan. the normal source of currentat the othenoiiice for actu-.- atinsaid relay vreg mrdless. of the direction of I the normal-currentpnsaidline, a. source. of-alternatingcurrent,and means responsive 1 to theactuation ofsaid relayfor connecting.

said source of alternating current tov said sleeve conductor fortheiransmission ofa,

signal from said source over saidsleeve cone ductaor.-,.

7 In; a signaling system, a. line,,means for signaling ineitherdirection over said line in response to a: current impulse, and.means for signaling in onedirection of said. line in response to a;current impulse of] 'hi-ghervoltage:

8. In a signaling system, a line, means:

for signaling in one direction over said'line in response to a currentimpulse ofa certain voltage, means for signaling in the oppositedirection over'said line in response to: acurrent impulse of thesamevoltage. and

reduced resistanceofthe line, and means for signaling in one directionover. the line 1nv response to av current impulse of: another voltage.

9. Ina signaling. system, a line, ,means for signaling ineitherdirection lover said line in response to a current impulse and: meansfor signaling in one direction-overv said line in response to a currentimpulse of a higher voltageregardless of the presence at theti ne whenthis last mentioned signal-v.

ing is initiated vof either of the. other signals on the line.

10. In a signaling, system, a line, .means. for 'signaling in eitherdirection over-said line'in response to. a currentv impulse, and meansfor disabling sa-id'signaling in either. direction-for signaling in onedirection over said :line in response. to another current .impulse. r

11. In .a signaling system, a .line,la .source.

of vcurrentnormally connected to: said I line,

means forsignaling inqone. direction over saidlineinresponse to animpulse from said: current source of a certain polarity, meansfox-signaling in theoppositedirection over. said line in response to acurrent impulse. from said source. of said. certain polarity RAUL B- PY;

